CYP2W1 is a so-called "ophan P450", a cytochrome P450 enzyme which has no defined function or endogenous/xenobiotic substrates. CYP2W1 has recently been shown to be selectively expressed in some forms of cancers and, with the low expression in normal tissues, could be rendered as a possible drug target during cancer therapy (Yoshioka et al. 2006). CYP2W1 can bioactivate several procarcinogens but at lower levels than other P450s. CYP2W1 also shows monooxygenase activity towards the pigment indole (INDOL), an ingredient of perfumes and coal tar.